More on variable flow piping

Engineers are doing everything to save energy for their clients by selecting the most efficient pump with the most efficient motor. These are responses to several questions that were not addressed during the live webcast.


Engineers are doing everything to save energy for their clients by selecting the most efficient pump with the most efficient motor. Courtesy: Grundfos Pumps Corp.

Several additional questions were left unanswered at the conclusion of the webcast on Sizing Variable Flow Piping: An Opportunity to Reduce Energy. Below are the most common questions and their respective answers. 

Question: How did you generate an accurate cooling load profile?

Kevin Anderson: Trane TRACE or Carrier Hourly Analysis Program (HAP) can be used to develop the load profile. The information will be based on the location and design of the facility.

Question: Can you go into more detail into the back flow when using old three-way valves in variable flow piping?

Kevin Anderson: Three-way valves are designed for equal pressure in constant speed/constant volume systems in zoned applications with a bypass. When switching to a variable speed/variable volume system, the bypass is not needed. Once the bypass is disabled, the back pressure may lift the old three-way valve off the seat. Flow that should go to the return could go backwards through other zones depending on design.

Question: When would you use copper pipe versus steel pipe?

Kevin Anderson: In closed loop systems, either copper or steel piping configurations can be used. In open systems for potable water, copper piping is recommended.

Question: Can you really install two Alpha or Magna pumps in parallel? Can this work?

Kevin Anderson: Two Magna3 pumps can be mounted in parallel and can be configured to run at in alternating operation, backup operation, or cascade operation using either constant pressure or constant curve modes.

 Kevin Anderson is a senior technical training specialist at Grundfos Pumps Corp., Olathe, Kansas.Question: The difference price between 3- and 2.5-in. shouldn't that much that the smaller size to be selected. We want to use the pump and piping for the years. So for some example as such, we have to choose the bigger size. Is that right?

Kevin Anderson: The cost differential between 3- and 2.5-in. copper tubing can be $5/ft. This could result in substantial savings. As mentioned in the webinar, systems rarely operate at peak demand, making the smaller pipe a good choice in variable speed/variable volume systems.

Kevin Anderson is a senior technical training specialist at Grundfos Pumps Corp., Olathe, Kansas. 

Product of the Year
Consulting-Specifying Engineer's Product of the Year (POY) contest is the premier award for new products in the HVAC, fire, electrical, and...
40 Under Forty: Get Recognized
Consulting-Specifying Engineer magazine is dedicated to encouraging and recognizing the most talented young individuals...
MEP Giants Program
The MEP Giants program lists the top mechanical, electrical, plumbing, and fire protection engineering firms in the United States.
November 2018
Emergency power requirements, salary survey results, lighting controls, fire pumps, healthcare facilities, and more
October 2018
Approaches to building engineering, 2018 Commissioning Giants, integrated project delivery, improving construction efficiency, an IPD primer, collaborative projects, NFPA 13 sprinkler systems.
September 2018
Power boiler control, Product of the Year, power generation,and integration and interoperability
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
Data Center Design
Data centers, data closets, edge and cloud computing, co-location facilities, and similar topics are among the fastest-changing in the industry.
click me